Some of the clinical requirements of designing a radiosurgical treatment system include providing: a) a highly precise beam delivery to targets located throughout the body, b) a highly conformal dose distribution, c) the ability to irradiate both small and/or large complex shaped lesion. To do this, the system uses a combination of beam positions whose relative weights, or dose contributions, have been scaled to volumetrically shape the dose accordingly. One or more collimators can be selected to give the beams the diameters required to achieve the desired clinical result. Current radiation treatment surgery equipment such as the CYBERKNIFE® radiosurgery system, manufactured by Accuray™ Incorporated, USA relies on a set of 12 circular, fixed size secondary collimators to reduce the beam to the size required by the treatment planning algorithm. Currently changing of these collimators is accomplished manually by hand.
FIGS. 9 and 10 illustrate the conventional process of changing collimators manually. FIG. 9 shows a locking nut 901 being removed by unscrewing the locking nut and releasing the collimator. Subsequently, the collimator may be replaced by another collimator by screwing the locking nut. Changing collimators with this version of the CYBERKNIFE® radiosurgery system, manufactured by Accuray™ Incorporated, USA, the locking nut 901 has to be rotated by multiple turns of the hand to release the collimator from off the end of a Linear Accelerator (LINAC). FIG. 10 illustrates the collimator released from a collimator housing during a manual process of changing a collimator.
One conventional process for manually changing the collimators includes the following operations. First, the operator removes the locking nut 901 by unscrewing it from the collimator housing. Next, the operator, using his/her hand, supports the collimator from the bottom. Next, the operator releases a retaining pin to release the collimator from the collimator housing to the operator's hand. Next, the operator selects a different collimator and inserts the different collimator into the collimator housing until the retaining pin clicks. Lastly, the operator replaces the locking nut 901 by screwing the locking nut 901 to the collimator housing. In this conventional process, the locking nut 901 has to be turned multiple turns to be removed from the end of the LINAC.